Recently, as security becomes more important, a variety of security programs are used and also under development. Further, when personal information or copyrighted literary works are shared, a danger of information leakage becomes increased so that the importance of the security programs continues to be higher.
One of file management methods is to manage database access. Regarding how to manage files, a prior art of Korean registered Patent No. 10-1158336 (published on Jun. 22, 2012) discloses a method in which operations to copy, transfer, inquire and delete personal information are allowed only by authority granted for each virtual space directory.
However, in case of providing services to manage files, the files may be leaked when database is hacked, unless deleting the files. Further, when sharing copyrighted files, there is a possibility that the files may be redistributed by others having no copyright in a digital environment in which it is easy to copy and store the files.